Recent detection of the neutrino event, IceCube-170922A by IceCube observatory from the Blazar TXS 0506+056 in the state of enhanced gamma ray emission indicates for acceleration of cosmic rays in the blazar jet. The non-detection of the broadline emission in the optical spectrum of TXS 0506+056 and other BL Lac objects suggests that external photons emissions are weak and hence photo-meson (pγ) interaction may not be a favored mechanism for high energy neutrino production. The lack of broadline signatures also creates doubt about the presence of a high density cloud in the vicinity of the super-massive black hole (SMBH) of TXS 0506+056 and consequently raised question on hadronuclear (pp) interaction interpretation like relativistic jet meets with high density cloud. Here we demonstrate that non-relativistic protons in the proton blazar model, those come into existence under charge neutrality condition of the blazar jet, offer sufficient target matter for pp−interaction with shock accelerated protons and consequently the model can describe consistently the observed high energy gamma rays and neutrino signal from the blazar TXS 0506+056.PACS numbers: 96.50.S-, 98.70.Rz, 98.70.Sa

Recent detection of the neutrino events IceCube-170922A, 13 muon-neutrino events observed in 2014-2015 and IceCube-141209A by IceCube observatory from the Blazars, namely TXS 0506+056, PKS 0502+049/TXS 0506+056 and GB6 J1040+0617 respectively in the state of enhanced gammaray emission, indicates the acceleration of cosmic rays in the blazar jets. The photo-meson (pγ) interaction cannot explain the IceCube observations of 13 neutrino events. The non-detection of broadline emission in the optical spectra of the IceCube blazars, however, question the hadronuclear (pp) interaction interpretation through relativistic jet meets with high density cloud. In this work, we investigate the proton blazar model in which the non-relativistic protons that come into existence under the charge neutrality condition of the blazar jet can offer sufficient target matter for pp interaction with shock-accelerated protons, to describe the observed high-energy gamma-rays and neutrino signal from the said blazars. Our findings suggest that the model can explain consistently the observed electromagnetic spectrum in combination with appropriate number of neutrino events from the corresponding blazars.PACS numbers: 96.50.S-, 98.70.Rz, 98.70.Sa

It is widely believe that galactic cosmic rays are originated in supernova remnants (SNRs) where they are accelerated by diffusive shock acceleration process at supernova blast waves driven by expanding SNRs. In recent theoretical developments of the diffusive shock acceleration theory in SNRs, protons are expected to accelerate in SNRs at least up to the knee energy. If SNRs are true generator of cosmic rays, they should accelerate not only protons but also heavier nuclei with right proportion and the maximum energy of heavier nuclei should be atomic mass (Z) times that of protons. In this work we investigate the implications of acceleration of heavier nuclei in SNRs on energetic gamma rays those are produced in hadronic interaction of cosmic rays with ambient matter. Our findings suggest that the energy conversion efficiency has to be nearly double for the mixed cosmic ray composition instead of pure protons to explain the observation and secondly the gamma ray flux above few tens of TeV would be significantly higher if cosmic rays particles can attain energies Z times of the knee energy in lieu of 200 TeV, as suggested earlier for non-amplified magnetic fields. The two stated maximum energy paradigm will be discriminated in future by the upcoming gamma ray experiments like Cherenkov Telescope array (CTA).PACS numbers: 95.85.Ry, 95.85.Pw

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The nearest active radio galaxy Centaurus (Cen) A is a gamma ray emitter in GeV to TeV energy scale. The High Energy Stereoscopic System (H.E.S.S.) and non-simultaneous Fermi-LAT observation indicate an unusual spectral hardening above few GeV energies in the gamma-ray spectrum of Cen A. Very recently the H.E.S.S. observatory resolved the kilo parsec (kpc)-scale jets in Centaurus A at TeV energies. On the other hand the Pierre Auger Observatory (PAO) detects a few ultra high energy cosmic ray (UHECR) events from Cen-A. The proton blazar inspired model, which considers acceleration of both electrons and hadronic cosmic rays in AGN jet, can explain the observed coincident high energy neutrinos and gamma rays from Ice-cube detected AGN jets. Here we have employed the proton blazar inspired model to explain the observed GeV to TeV gamma-ray spectrum features including the spectrum hardening at GeV energies along with the PAO observation on cosmic rays from Cen-A. Our findings suggest that the model can explain consistently the observed electromagnetic spectrum in combination with the appropriate number of UHECRs from Cen A.